The present invention relates to new sweetening agents for sweetening food, drinks, confectionery, chewing gums, hygiene products, cosmetics, pharmaceutical and veterinary products, and the like. It also relates to the products and compositions containing such sweetening agents.
Among the chemical compounds presenting sweetening properties, "suosan" and its derivatives constitute a chemical series which has been widely studied since its discovery in 1948 by Petersen and Muller (See, for example, Beets, pp. 336-337, in "Structure-Activity Relationships in Human Chemoreception", Applied Science Publ., London, 1978; Crosby and Wingard, p. 160, in "Developments in Sweeteners", Applied Science Publ., London, 1979; Tinti, Nofre and Peytavi, Z. Lebensm. Unters. Forsch., 175, 266-268, 1982). These compounds have not been put to commercial use as sweeteners because: (1) certain of them release potentially toxic molecules ("suosan", for example, can give rise to p-nitroaniline); (2) certain of them contain ureido or thioureido groups which undergo slow hydrolysis in aqueous solution; and (3) certain others, apart from their sweet taste, generate undesirable liquorice or bitter aftertastes.
Of further interest to the present invention is the disclosure of Yuki and Inoue (Nippon Kagaku Kaishi, no. 11, 2140-43 (1974)), Chemical Abstracts, Vol. 82, no. 140061p (1975) which describes N-((4-chlorophenylamino)iminomethyl)-.beta.-alanine (Chemical Substance Index, vol. 76-85, 1972-1976, p. 1067cs). This compound fails to present the high potency sweetening properties of the compounds of the present invention.
Also of interest to the present invention are the disclosures of the inventors in their own European patent application No. 0,107,597 published May 2, 1984 (U.S. Pat. No. 4,645,678) and European patent application No. 0,195,731 published Sept. 24, 1986 corresponding to French patent application No. 85.04241. These applications disclose suosan derivatives characterized by the replacement of the beta-alanine group present in the suosan molecule with sweet dipeptide ester moieties such as aspartame (L-aspartyl-L-phenylalanine methyl ester). The sweet suosan/dipeptide derivatives disclosed by the above two patent applications are also characterized by replacement of the oxygen defining the urea structure by sulfur to form a thiourea, by a nitrogen to form a guanidine or by a carbon to form an amidine structure. Such compounds, while disclosed as having sweetness potencies as high as 55,000 times that of a 2% sucrose solution on a by weight basis, suffer from limitations relating to solubility and/or instability in the presence of elevated temperatures. The sweetening potency of aspartame, by comparison, is about 180 times that of a 2% sucrose solution on a by weight basis.